I n s i t u detection of BH2 and atomic boron by intracavity laser spectroscopy in the plasma dissociation of gaseous B2H6

Absorption spectra of the BH2 radical and atomic B are detected by intracavity laser spectroscopy (ILS) in situ during the plasma dissociation of gaseous diborane (B2H6). Rovibronic absorption transitions of BH2 are observed near 15 469 cm−1 [(0,11,0)2B′1 –(0,0,0)2A″1] and 13 605 cm−1 [(0,9,0)2B′1 –(0,0,0)2A″1]. Absorption corresponding to the 3p (2P0)-5s (2S) transitions of atomic B are observed at 11 534.6 and 11 532.8 cm−1. Although atomic B has been detected previously under experimental conditions used in the plasma-assisted preparation of boron-containing films from B2H6, the ILS data presented here establish, for the first time, the presence of BH2 under chemical vapor deposition conditions.